Field of the Invention
The present invention relates to an ophthalmologic apparatus for measuring ocular characteristics of an eye to be inspected or acquiring an image of the eye to be inspected, and to an alignment method for the ophthalmologic apparatus.
Description of the Related Art
In conventional ophthalmologic apparatus for measuring ocular characteristics of an eye to be inspected, automatic alignment has been known to be performed by projecting a light beam to a cornea of the eye to be inspected and detecting a reflection image of the light beam by a light receiving element to determine an alignment status between the eye and an optical system of the apparatus.
In the ophthalmologic apparatus disclosed in Japanese Patent No. 3576656, a method is disclosed in which the three-dimensional position information on the eye and the optical system of the apparatus is detected from a positional relationship of the reflection image that is received after being separated by a pair of light deflecting members.
In the ophthalmologic apparatus disclosed in Japanese Patent No. 4769365, in order to allow high-precision automatic alignment in a wide range, there has been known a method in which the cornea of the eye to be inspected is irradiated with light beams from an optical axis direction and a direction different from an optical axis to perform the automatic alignment based on reflection images of the light beams.
A cataract patient has surgery to implant an intraocular lens (IOL) in place of a crystalline lens.
However, the IOL has a refractive index higher than that of the crystalline lens, and the light beam projected to the cornea is reflected as IOL reflection light. Therefore, there has been a problem in which an IOL reflection ghost is incorrectly detected as an original alignment reflection image and the automatic alignment is not completed normally.
Therefore, when the automatic alignment has failed, an inspector manually aligns the apparatus for measurement, and hence the measurement takes time.